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Full text of "Tools"

Hydraulic Espresso Tamper 



Makej Projects 



Hydraulic Espresso Tamper 

Written By: John Edgar Park 



TOOLS: 

Angle grinder (1) 

to cut and smooth aluminum 

Crescent wrench (1) 

Drill press (1) 

Hex wrench (1) 

for juicer disassembly 

Needlenose pliers (1) 

to remove lever handle retention clip 

Tap wrench (1) 



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PARTS: 

Juicer (1) 

around $20 from department store 

clearance sales or ebay.com 

Espresso tamper base (1) 

you may be able to unscrew the handle 

of your current tamper, or buy one at 

coffeetamper. com. 

Actuator piston (1) 

See what you can find at the salvage 

yard, or search eBay.com for a 1" 

Parker actuator. 

Pressure gauge (1) 

Try a local metal supply or order from 

Small Parts (smallparts.com). 

Bar stock (1) 

Fittings (1) 

to connect pistons to gauge 

Piped) 

to connect pistons to gauge 

Oil (1) 

Either makes good hydraulic fluid, and 
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Hydraulic Espresso Tamper 



neither si )ison you! 

Threaded insert (1) 
Thumbscrew or bolt (1) 



SUMMARY 

Godshot. That's the elusive goal of espresso fanatics everywhere. Thick with micro-bubble 
crema and a velvety mouth-feel, and packing explosive flavor, the godshot is pulled too 
infrequently for my liking. A perfect shot of espresso is the product of many variables, so 
anything I can do to lock in one of those variables is a good thing. Think scientific method as 
applied to espresso. 



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Hydraulic Espresso Tamper 



Step 1 — Isolate your factors. 




• As a home barista, the 5 factors I worry about most are: beans, water, grind, dosing, and 
tamping. Here's a quick overview: 

• Beans: Use high-quality beans that have been roasted within the past 3 days to 2 
weeks. 

• Water: Fresh water needs to be brought up to proper temperature and pressure by the 
espresso machine. 

• Grind: Dial in your burr grinder to fine-tune the coarseness of the ground beans. 

• Dosing: There's a prescribed amount of grounds to measure into a standard portafilter 
basket, but people tinker with this all the time. 

• Tamping: Once the grounds have been measured into the portafilter and distributed 
evenly, they should be compressed with 30 pounds of pressure using a tamper. This is 
difficult to do by hand. 

• Once these steps have been taken, the portafilter is locked into the group head of the 
espresso machine and the shot is pulled. This is sometimes accompanied by breath 
holding, finger crossing, and the like. 



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Hydraulic Espresso Tamper 



Step 2 — Consider your variable. 




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Hydraulic Espresso Tamper 

• The variable I chose to attack was the problem of tamping. I'd heard about automated 
tamping systems, which remove the guesswork of manually pressing grounds into the 
portafilter with a handheld tamper, and instead consistently provide 30 pounds of uniform 
pressure. This is great, but automatic tamping machines cost hundreds of dollars. One 
clever member of the http://www.home-barista.com forums scoffed at the price tag and 
built his own, using a manual lever juicer as the platform. I decided to give it a try. 

• I considered a few requirements for my auto tamper: a way to know when I've hit the 
magic 30lbs, a way to secure a commercial tamper base to the down-shaft of the juicer, 
and a method of resting different portafilters with their oddly shaped undersides on a load- 
bearing surface. 

• Through some informal research, I determined that the most common method of indicating 
correct pressure in a commercial auto tamper is with a "clicker" system. This is a 
calibrated spring and ball bearing mounted at a right angle to the shaft. One great feature 
of these systems is that they stop all downward pressure after the threshold has been met. 

• Home baristas have more commonly opted for a heavy spring mounted over the juicer 
shaft, kind of like a car's coil-over suspension. Enlisting the aid of a bathroom scale, they 
test for the 301b depth and then mark a calibration line on the shaft. This is an elegant, 
simple design, and they've reported excellent results. Another simple method, suggested 
by a gearhead friend of mine, would be to replace the lever handle on the juicer with a 
torque wrench adjusted to pop when 30lbs are measured at the tamper. 

• While the torque wrench would have functioned well, I was also concerned with aesthetics. 
I wanted to maintain the quasi-steampunk look of my espresso machine, with its beautiful 
pressure gauges front-and-center. I wondered how I could use an analog dial to read out 
my tamping force. After another brainstorming session with my friend, we had it: a 
pressure gauge connected to a hydraulic piston coupled between the juicer's down-shaft 
and the tamper base. 



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Hydraulic Espresso Tamper 



Step 3 — Find your materials. 




• The total cost should be $60-$100, 
depending on where you find your 
parts. 

• The foundation for the project is the 
juicer. It can be had for about $20 
at T.J. Maxx or Marshalls, and I 
also found many on eBay — just 
search for " manual juicer ." 

• The piston, gauge, and fittings 
proved a bit harder to track down. I 
found many sources online, but 
they were all too expensive. I 
finally hit the jackpot at Norton 
Sales ( http://nortonsalesinc.com ), 
an aerospace scrap yard in North 
Hollywood, Calif. There, I picked up 
a stainless steel actuator piston for 
$5, a 100psi gauge for $7, and the 
pipe and fittings for a few bucks. 

• I went to Industrial Metal Supply 
( http://imsmetals.com ) for scrap 
aluminum stock. A neat little store 
in Burbank, Calif., called Luky's 
Hardware yielded various bolts, 
inserts, taps, and cheap, 
resharpened drill bits. 



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Hydraulic Espresso Tamper 



Step 4 — Begin construction. 






• To begin construction, I disassembled the juicer and its down-shaft. I then removed the 
lever handle, placed the down-shaft at its highest point, and re-inserted the lever handle at 
a better starting angle. 

Step 5 




• Next, I drilled and tapped a 1 1 /2" length of 1" aluminum rod to couple together the juicer's 
shaft and the piston's mounting thread. If you don't want to drill and tap solid bar stock, 
you could consider using a tube with some cross-drilled tightening bolts instead. 

• I couldn't find an insert of the correct dimensions to mate the piston rod to my commercial 
tamper base. I found one that was very close, and cut it with a die to fit the coarse 
threading of my tamper. A bit of a hack, but it seems to work well enough. If you're willing 
to re-tap your tamper base, you'll have a wider variety of inserts to choose from. 



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Hydraulic Espresso Tamper 



Step 6 




• I filled the piston with glycerin, my food-safe hydraulic fluid of choice, and then screwed in 
all the fittings for the pipe, gauge, and piston (including a plug for the upstroke inlet). I left 
a bit of air in the line to provide a little compression. I found that it feels better to have 
some give as you pull down on the lever. If this were a car, you'd call it mushy brakes. 

• Thread the insert into the tamper base to join it to the actuator piston. 



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Hydraulic Espresso Tamper 



Step 7 — Build the base. 




• Since I use both regular and bottomless portafilters (see MAKE, Volume 04, page 117, 
"The Bottomless Portafilter" to build your own), I needed a versatile enough base plate to 
support either of them during tamping. I cut a 5" length of my rectangular aluminum stock 
with a grinder, and then cut a U-shaped section out of it. I made this wide enough to clear 
the underside of a regular portafilter but still support the bottomless one. 

• I drilled a 3 A" hole at one end of the plate so I could slide it over the juicer's support 
column. Finally, I drilled and tapped a 3/8" hole at the back of the plate. This allows me to 
tighten it in place with a small bolt. 

• Now pull the lever to tamp your grounds, while keeping an eye on the pressure gauge. 
Perfect tamping! 

• With everything assembled, I've now got my own auto tamper for about $50 — far less 
than a commercial unit. It functions flawlessly, gives me an exact tamp every time, and 
looks stylish. But most importantly, it's removed tamping from my list of espresso worries 
in the continued quest for the godshot. 



This project first appeared in MAKE Volume 12 . page 125. 



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